I have had my Nook Tablet for just over a month. Have not had to recharge the battery often, but yesterday when I got the message to charge it, I charged it overnight and this morning my battery was only at 80%. Please advise. I'm heading off to the B&N store today, because I feel this is unacceptable.

The cables are notoriously fragile. The advice to take the cable AND charger in to B&N is good. They may change it outright if you have both pieces.

One clue can be the LED colors on the cable. It should be off when disconnected from the NOOK, yellow(ish) while charging, and green when fully charge. On one defective cable I had, it would glow red when disconnected, and a half-hearted green while charging. They changed it at the store with minimal fuss.